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Home >> Subaru >> 2014 >> BRZ Premium >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System (Heater, Ventilator And A/C) >> Heater & Air Conditioner System (For Automatic Air Conditioning System) >> Function Inspection

Function Inspection

  1. Check of cooling performance
    1. Install the air conditioner tool set to the vehicle.
    2. Set the vehicle to the following conditions.[*1]
      Item Conditions
      Vehicle body Vehicle parked condition in shade
      Door Full open
      A/C switch ON
      Engine speed 2000 r/min
      FRESH/RECIRC damper position RECIRC position
      Outlet opening damper position FACE
      Setting temperature LO (MAX COLD)
      Blower speed HI
      Air conditioner inlet opening temperature (1) 30 to 35°C {86 to 95°F}
      Condenser pressure (gauge high pressure side) (1) 1.47 to 1.67 MPaG (15 to 17 kgf/cm2 )
      (1) The inlet opening temperature can be judged correctly only in the range from 30 to 35°C {86 to 95°F}. If the temperature is low, postpone the test.
      (2) If the condenser pressure (gauge high pressure side) is high, reduce the pressure by watering the condenser. If it is too low, increase the pressure by placing a cover over the condenser.
    3. Place a wet-and-dry-bulb thermometer (necessary for humidity) at the inlet opening and measure the temperature by inserting the bulb of the dry thermometer at the center of the outlet opening.
    4. Operate the air conditioner under the conditions in [*1] to make the outlet opening temperature stable. (About 5 to 6 minutes)
    5. Measure the dry and wet bulb temperatures at the inlet opening and the temperature at the outlet opening.
    6. Apply the measurement values of the dry/wet bulb temperatures at the inlet opening to the air diagram to obtain the relative humidity.
      Fig 1: Dry/Wet Bulb Temperatures Measurement Values Graph
      G08553412Courtesy of SUBARU OF AMERICA, INC.
      1. For relative humidity, when the dry bulb temperature of the wet-and-dry-bulb thermometer at the inlet opening is 25°C {77°F} and the wet bulb temperature is 19.5°C {67.1°F}, the intersection of the broken lines in the figure is the relative humidity. In this case, it is 60%.
        Fig 2: Dry/Wet Bulb Temperatures Relative Humidity Graph
        G08553413Courtesy of SUBARU OF AMERICA, INC.
    7. Check the cooling performance by applying the difference of measured temperatures between the inlet opening and outlet opening and the relative humidity to the standard performance table.
      Fig 3: Cooling Performance Graph
      G08553414Courtesy of SUBARU OF AMERICA, INC.

      Criteria: The value must be within the shaded area of the diagram.

      1. To obtain the cooling performance using the standard performance table, an example when the difference of temperatures between the inlet opening and the outlet opening is 17°C {30.6°F} and the relative humidity is 60% is shown below.
        Fig 4: Cooling Performance Graph
        G08553415Courtesy of SUBARU OF AMERICA, INC.
  2. Check of refrigerant gas pressure
    1. Check of refrigerant gas pressure with gauge
    Fig 5: Refrigerant Gas Pressure Graph
    G08553416Courtesy of SUBARU OF AMERICA, INC.
    1. Attach the air conditioner tool set.
    2. Set the vehicle to the following conditions.[*2]
      Item Conditions
      Engine After warming-up
      Door Full open
      A/C switch ON
      RECIRC switch Recirculation
      Setting temperature LO
      Blower speed HI
      Air conditioner inlet opening temperature 30 to 35°C {86 to 95°F}
    3. Check the gauge value in [*2].
      1. At normal condition

        Standard value: 0.13 to 0.20 MPa (1.3 to 2.0 kgf/cm2 ) (Low pressure side)

        1.47 to 1.67 MPa (15 to 17 kgf/cm2 ) (High pressure side)

        Fig 6: Refrigerant Gas Pressure Gauge Value - At Normal Condition
        G08553417Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge at normal charge level of refrigerant gas.
    4. In malfunction
      1. Example: During operation of the air conditioner, the pressure at the low pressure side becomes vacuum or normal.
        MEASUREMENT RESULT

        Symptoms It becomes cold or not cold cyclically.
        Cause Moisture in the cooling system is frozen at the cooler expansion valve. The refrigerant does not circulate temporarily. After ice is melted, normal operation is recovered.
        Diagnosis
        • The cooler drier is over-saturated.
        • Moisture of the cooling system is frozen at the expansion valve and it blocks circulation of the refrigerant gas.
        Corrective action
        • Replace the cooler dryer.
        • Remove moisture in the cycle by repeating air release.
        • Inject appropriate level of new refrigerant gas.
        Fig 7: Refrigerant Gas Pressure Gauge Value - During Operation Of Air Conditioner, Pressure At Low Pressure Side Becomes Vacuum Or Normal
        G08553418Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge condition of moisture inclusion in the cooling system.
      2. Example: Both high and low pressure sides are low.
        MEASUREMENT RESULT

        Symptoms
        • Poor cooling performance
        • Cooling performance is not sufficient.
        Cause A part of the cooling system has gas leak.
        Diagnosis
        • Refrigerant gas is insufficient.
        • Leak of refrigerant gas
        Corrective action
        • Check for gas leak. Repair it if necessary.
        • Inject appropriate level of new refrigerant gas.
        • If the pressure value is close to 0 when connected to the gauge, check for the leak area. After repair, perform vacuuming.
        Fig 8: Refrigerant Gas Pressure Gauge Value - Both High And Low Pressure Sides Are Low
        G08553419Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge condition of poor cooling.
      3. Example: The pressures at both low and high pressure sides are low and the pipe connected from the cooler condenser assembly to the air conditioner unit has condensation.
        MEASUREMENT RESULT

        Symptoms Poor cooling performance
        Cause Dust in the cooler condenser core blocks flow of refrigerant.
        Diagnosis Clogged cooler condenser core
        Corrective action Replace the cooler condenser assembly.
        Fig 9: Refrigerant Gas Pressure Gauge Value - Pressures At Both Low And High Pressure Sides Are Low And Pipe Connected From Cooler Condenser assembly To Air Conditioner Unit Has Condensation
        G08553420Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge condition of poor refrigerant gas performance.
      4. Example: Pressures at both low and high pressure sides are low and the pipe before and after the cooler condenser core and the cooler expansion valve has fogging or condensation.
        MEASUREMENT RESULT

        Symptoms Poor cooling (it may work in cases)
        Cause
        • Flow of the refrigerant gas is blocked by moisture or dust of the cooling system.
        • Flow of the refrigerant gas is blocked by leak of the refrigerant gas from the cooler expansion valve.
        Diagnosis Refrigerant gas does not circulate.
        Corrective action
        • Check the cooler expansion valve.
        • Remove dust in the cooler expansion valve with an air gun.
        • Replace the cooler condenser assembly.
        • After vacuuming, inject new refrigerant gas to the appropriate level.
        • If leak of the refrigerant gas from the cooler expansion valve is found, replace the cooler expansion valve.
        Fig 10: Refrigerant Gas Pressure Gauge Value - Pressures At Both Low And High Pressure Sides Are Low And Pipe Before And After Cooler Condenser Core And Cooler Expansion Valve Has Fogging Or Condensation
        G08553421Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge for no circulation of the refrigerant gas.
      5. Example: Both high and low pressure sides are too high.
        MEASUREMENT RESULT

        Symptoms Poor cooling performance
        Cause
        • Flow of the refrigerant gas is blocked by moisture or dust of the cooling system.
        • Flow of the refrigerant gas is blocked by leak of the refrigerant gas from the cooler expansion valve.
        Diagnosis
        • Excessive refrigerant
        • Cooling of the cooler condenser core is insufficient.
        Corrective action
        • Clean the cooler condenser core fin.
        • Check operation of the cooling fan.
        • Check the refrigerant level and inject the refrigerant to the appropriate level.
        Fig 11: Refrigerant Gas Pressure Gauge Value - Both High And Low Pressure Sides Are Too High
        G08553422Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge condition of excess refrigerant gas or insufficient cooling of the cooler condenser core.
      6. Example: Pressures at both low and high pressure sides are high and the low pressure pipe is too hot to be touched.
        Fig 12: Refrigerant Gas Pressure Gauge Value - Pressures At Both Low And High Pressure Sides Are High And Low Pressure Pipe Is Too Hot To Be Touched
        G08553423Courtesy of SUBARU OF AMERICA, INC.
        MEASUREMENT RESULT

        Symptoms Air conditioner does not function.
        Cause Air inside the cooling system
        Diagnosis
        • Air is included inside the cooling system.
        • Insufficient vacuuming
        Corrective action
        • Check if the compressor oil is contaminated or insufficient.
        • After vacuuming, inject new refrigerant gas.
        NOTE:
        • CAUTION: The gauge indicates a value when the cooling system is opened without vacuuming for injection of the refrigerant.
        • The illustration indicates the gauge condition of air inclusion in the cooling system.
      7. Example: Pressures at both low and high pressure sides are high and the low pressure side has fogging or condensation.
        MEASUREMENT RESULT

        Symptoms Poor cooling performance
        Cause Problems on cooler expansion valve
        Diagnosis
        • Excessive refrigerant of low pressure pipe
        • Excessive opening of cooler expansion valve
        Corrective action Replace the cooler expansion valve.
        Fig 13: Refrigerant Gas Pressure Gauge Value - Pressures At Both Low And High Pressure Sides Are High And Low Pressure Side Has Fogging Or Condensation
        G08553424Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge of improper cooler expansion valve.
      8. Example: Pressure at the low pressure side is high and pressure at the high pressure side is low.
        MEASUREMENT RESULT

        Symptoms Air conditioner does not function.
        Cause Compression leak in cooler compressor assembly
        Diagnosis
        • Poor compression
        • Leak from valve or damage to sliding part
        Corrective action Repair or replace the cooler compressor assembly.
        Fig 14: Refrigerant Gas Pressure Gauge Value - Pressure At Low Pressure Side Is High And Pressure At High Pressure Side Is Low
        G08553425Courtesy of SUBARU OF AMERICA, INC.
        NOTE: The illustration indicates the gauge of poor compression of the cooler compressor assembly.
  3. Cooler condenser assembly
    1. If the cooler condenser assembly fin is contaminated, clean it with water and dry it with compressor air.
      CAUTION: Do not damage the fin of the cooler condenser assembly.
    2. If the fin of the cooler condenser assembly is bent, correct the fin straight with a screwdriver or pliers.
  4. Check for refrigerant gas leak
    1. Using a halogen leak detector, check the pipe joints for leaks.
    2. If gas leak is found at joints of pipes, check the torque at the joints.
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